Fabrication and Properties of Poly(Vinyl Alcohol)Composites With Carbon Nanotubes and Inorganic Fillers

Abstract

Researchers from all over the world have taken a keen interest in the development of new composite materials having improved properties at low cost. Although, many of the problems of modern era in the field of material science have been addressed due to extensive research by the material scientists, yet there is still margin of work for interested scientists. In the present study an effort has been made to contribute to the existing knowledge by synthesizing new composites/nanocomposites and their subsequent characterization, employing latest state of the art analytical equipment. Poly (vinyl alcohol) (PVA) and alumina (Al2O3) based composites, having varying amount of lithium perchlorate (LiClO4), were synthesized in aqueous medium by employing the acid catalyzed sol-gel method. Aluminum butoxide was used as precursor for preparation of alumina. PVA and multiwalled nanotubes (MWNT), and, PVA and double walled nanotubes (DWNT) based nanocomposites were fabricated with the help of functionalized carbon nanotubes (CNTs). CNTs were functionalized using nitric acid method. Cetyltrimethylammonium bromide (CTAB) was used as surfactant. LiClO4 in different proportions were added at the end fabrication procedure. Final thin film composites were obtained by solvent casting technique. Thermogravimetric Analysis (TGA), Tensile Properties, Scanning Electron Microscopy (SEM), X-ray Diffractometry (XRD), and Fourier Transform Infrared (FTIR) spectroscopy were used for the characterization. Thermal Studies showed that PVA-Al2O3/LiClO4 composites were most stable among the three composite series, while PVA-DWNT/LiClO4 were least stable. PAL6 composite was the most stable composite with degradation temperature (TD) of 327.0 ˚C, whereas the least stable was PDL10 with TD of 291.5 ˚C. During mechanical studies, highest and lowest value of Young’s modulus were observed for PDL4 (1654.0 N.mm-2) and PAL10 (7.62 N.mm-2), respectively. Maximum value, 61.0 N.mm-2, for tensile strength was shown by PML10, whereas, minimum value, 8.82 N.mm-2, was observed for PAL2. Highest value, 174.59 mm, for elongation at break was shown by PAL4, while, lowest value, 69.4 mm, was that of PDL10. Overall, addition of lithium perchlorate had enhanced Young’s modulus and tensile strength of PVA-DWNT series and elongation at break of PVA-Al2O3 series. SEM studies on all three nanocomposite series revealed that Al2O3, MWNT, DWNT and lithium chlorate were well dispersed in the polymer matrix and surface of all the resulting polymer nanocomposites were smooth, bearing no holes or roughness. It has been found during XRD studies that addition of LiClO4 had increased crystallinity of PVA-Al2O3 series, while it had negative effect on the PVA-MWNT and PVA-DWNT nanocomposite series. It was concluded that MWNT and DWNT decreased the crystallinity while LiClO4 improved crystallinity of the resulting composite. FTIR test results showed that alumina, MWNT and DWNT has interacted chemically with the PVA. Lithium perchlorate also played its role in the chemistry of the PVA based composites. In the present study, we have successfully prepared thin Films of PVA-Al2O3/LiClO4, PVA-MWNT/LiClO4 and PVA-DWNT/LiClO4 nanocomposites which are thermally stable and with good strength. Best choice of properties, among the three composite series is provided by the PVA-DWNT/LiClO4 nanocomposites. Since water was used as solvent throughout the studies, our synthetic procedure is environment friendly.